With “Boulevard,” her latest exhibition at Fraenkel Gallery, Katy Grannan continues her subtle subversion of the idioms and codes of portraiture, a titillating project that has invariably drawn her to the marginal and marginalized, documenting an ever-expanding cast of offbeat characters and social outcasts ranging from the banal to the poignantly strange. As in previous work, Grannan’s images traffic in a poetic awkwardness that stops just short of the grotesque, and it is this finely honed sensibilitywhich mixes prurience and detached observationthat has positioned Grannan, rightfully or not, as the heir apparent to Diane Arbus. The show’s press release does little to dispel the connection, lasciviously touting the artist’s new series of “hustlers, strutters, addicts and beauty queens” captured on the streets of Los Angeles and in San Francisco’s Tenderloin district.